Cannot Run Online Update: Package Management Failed

I am trying to perform an Online Update remotely.

Initially I had connected to my server using vnc.

I used a user account, and saw there were packages to installed in the system tray.

However, when I clicked on the package notification, an alert popped up:

Failed to update system: Authorisation could not be obtained

I disconnected from the vnc session because it was running so slowly and reconnected with ssh and yast2.

I tried to do the online update as su however, it reports:

Accessing the Package Management Failed
Another process is accessing the the package database.
Package Management cannot be used now.

What do I do?